Date

diffuse sampling Articles

Indoor and outdoor gas hazards that exist in open areas are usually monitored using diffusion-type sensors. A diffusion sensor has no active sample-drawing system; diffusion sensors rely on the ambient air movement and pressure to deliver the sample to the sensing element. Diffusion-type sensors are a reliable and cost-effective way to monitor open area gas hazards. When installing diffusion ...

On March 30th 2015 a long freight train, transporting a variety of goods including lumber and chemicals, wound its way through the state of Mississippi. At around 5pm, part of the train failed to negotiate a curved portion of the track in a rural area near Minter City, resulting in the derailment of nine railcars, one of which leaked chemicals onto agricultural farmland and woodlands. Emergency ...

The ITRC in conjunction with the USGS, US EPA, US Army Corp of Engineers, and other prominent federal and state groups have released a comprehensive document, based on significant case studies and backed up by controlled laboratory testing, for the use of polyethylene membrane passive diffusion samplers, such as the EQUILIBRATOR Diffusion Sampler manufactured by EON Products, Inc. Part 1 of the ...

This document is intended to facilitate the use of polyethylene diffusion bag (PDB) samplers for long-term monitoring (LTM). The guidelines presented in Sections 2 and 3 relate to appropriate implementation, data interpretation, and regulatory issues of concern. Although diffusion samplers can be useful for many different activities and have membranes composed of various materials, this ...

Polyethylene diffusion bag (PDB) samplers are low-density polyethylene bags containing deionized water, used to collect water samples in groundwater wells for laboratory analyses of volatile organic compounds (VOCs). PDB samplers are passive devices, relying on the movement of groundwater from the aquifer or water-bearing zone through the screen or open interval of a well. VOCs in groundwater ...

Parsons Engineering Science, Inc. (Parsons ES) was retained by the US Air Force Center for Environmental Excellence Technology Transfer Division (AFCEE/ERT) to perform an evaluation of passive groundwater diffusion sampling technology. The diffusion sampler evaluation was funded under Contract F11623-94-D0024, Delivery Order RL72, as part of the AFCEE/ERT Remedial Process Optimization (RPO) ...

As has been previously discussed (1), FTIR spectroscopy is emerging as a technique that can be effectively used for applications and/or in locations that heretofore would be considered too demanding. The development of portable FTIRs, and more recently handheld FTIRs, is significant because it enables this powerful analytical technique to solve problems for a whole range of new applications, both ...

Solid–like non–ergodic samples can be difficult to study using standard single speckle diffusing wave spectroscopy as the measurement may lack requisite ensemble averaging. We demonstrate here that this required ensemble averaging can be induced by translating the speckle over the collection optics so that multiple speckles are observed over the duration of the experiment. Translation is achieved ...

The aim of the work is to verify the diffusion rate of ammonia through the Nalophan™ film that constitutes the sampling bag, considering storage times ranging from 1 to 26 h. The ammonia decay over time was evaluated using gas-chromatography for the quantification of ammonia concentration inside the bag. The research assesses the roles of both of ammonia and water concentration gradients ...

Environmental tobacco smoke (ETS) is associated with an increased risk of several diseases. In 2002, the ETS exposure level was studied in a Finnish cross-sectional population sample with a sub-sample of currently working nonsmokers. In all, 123 nonsmokers (25-64 years) reporting at least 1 h of daily exposure to ETS participated in personal exposure measurements. Two 3 M organic vapor monitors, ...

Field trials of a new commercially available diffusive ground-water sampling device were conducted at two industrial properties in the Blue Ridge Province of North Carolina. The test sites have extensive monitoring well networks and more than five years of historical water quality data. Volatile organic compounds (VOCs) including purgeable aromatics (petroleum hydrocarbons) and halogens ...

Analysis of deep-sea sediments presents a number of exceptional challenges. Generally, the amount of material available is small and has to be shared among investigators. Also, deep-sea sediment contains a diverse range of components from a variety of sources including lithogenous, biogenous and hydrogenous. Finally, large number of samples is frequently analysed making rapid analysis a ...

A conceptual challenge in exploring the role of interorganisational relationships is adapting an inherently level-ambiguous concept to incorporate distinct interpersonal- and interorganisational-level concepts. As compared to studies that have focused on large enterprises in developed countries, we define technology diffusion of small-sized firms whose resources are limited as distinct constructs ...

Received for publication February 3, 2008. Today there are many well-established computer models that are being used at different spatial and temporal scales to describe water, sediment, and P transport from diffuse sources. In this review, we describe how diffuse P models are commonly being used in the United States and Europe, the challenge presented by different temporal and spatial scales, ...

This document presents technical overviews of 12 passive sampling technologies. It describes each technology’s basis of operation, intended applications, advantages, limitations, and development status. Contacts for additional information are provided. This overview is an outgrowth of interest and information generated in preparation of the ITRC Technical and Regulatory Guidance for Using ...

ABSTRACT The current advisory for active soil gas investigations in California requires leak tests to be conducted at eveiy soil gas probe while taking a sample. A leak may allow ambient ak into the sample train thus diluting the soil gas and underestimating the results. Also, the leak check compound itself may have impurities thereby contaminating the sample. The advisoiy suggests leak ...

Saxitoxin (STX) is the most toxic non-protein substance known. STX-producing cyanobacteria have been identified in most continents and are being detected more widely because of global warming, threatening human drinking water supplies worldwide. Removal of these components can be accomplished by adsorption on granular-activated carbon (GAC) but little is yet known about the kinetics of the ...

Abstract Sampling indoor air for potential vapor intrusion impacts using current standard 24-hour sample collection methods may not adequately account for temporal variability and detect contamination best represented by long-term sampling periods. Mr. Henry Schuver of the U.S. Environmental Protection Agency (EPA) Office of Solid Waste staled at the September 2007 Air & Waste Management ...

The objective of this study was to evaluate the factors that affect the formation and diffusion of disinfection by-products, especially trihalomethanes (THM), in a laboratory-scale water distribution network constructed with three different pipe materials. Sampling locations were chosen on the basis of residence time, pipe material and mixing zone. Water samples were collected and analyzed for ...

Overlying water and sediment samples were collected from 11 locations in Ulansuhai Lake in June of 2012 to determine the concentration of dissolved inorganic phosphorus (DIP) in the interstitial water, overlying water and sediment and to estimate the diffusion flux of DIP at the sediment–water interface. The DIP levels in overlying water were 0.004–0.185 mg/L (average = 0.062 mg/L), while they ...

Need help finding the right suppliers? Try XPRT Sourcing. Let the XPRTs do the work for you

Subscribe to our eBulletins

Join our growing community of environmental professionals who are currently subscribed to weekly newsletters, product alerts, job alerts, and our monthly event updates and article newsletters. Stay up-to-date with the global environmental industry. Sign up for one or all of our free newsletters and alerts today.